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Related Experiment Videos

Is ATP Required for K+ Channel Activation in Vicia Guard Cells?

W. H. Wu1, S. M. Assmann

  • 1Department of Biology, The Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania 16802.

Plant Physiology
|January 1, 1995
PubMed
Summary

Adenosine triphosphate (ATP) is essential for activating inward-rectifying potassium channels in Vicia faba guard cells. This study reveals ATP

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Area of Science:

  • Plant Physiology
  • Cell Biology
  • Ion Transport

Background:

  • Inward-rectifying K+ channels in guard cells facilitate K+ entry, crucial for stomatal function.
  • This process is indirectly regulated by adenosine triphosphate (ATP) through an H+-ATPase, which hyperpolarizes guard cell membranes.

Purpose of the Study:

  • To investigate the direct requirement of ATP for the activation of K+ channels in Vicia faba guard cells.
  • To elucidate the role of ATP in regulating the activity of these specific ion channels.

Main Methods:

  • Utilized whole-cell and single-channel patch-clamp electrophysiology techniques.
  • Applied exogenous nucleotides (ATP, ADP, adenosine-5'-O-(3-thiotriphosphate)) and metabolic inhibitors (azide, glucose plus hexokinase).
  • Examined effects on inward K+ currents and single-channel activity in Vicia faba guard cell plasma membranes.

Main Results:

  • Cytoplasmic application of ATP, ADP, or adenosine-5'-O-(3-thiotriphosphate) did not affect whole-cell K+ currents.
  • An ATP-scavenging system (glucose plus hexokinase) significantly inhibited whole-cell inward K+ currents.
  • Single-channel recordings from inside-out patches demonstrated direct activation of inward K+ channels by ATP, which was reversible by the ATP-scavenging system.

Conclusions:

  • A low concentration of ATP is directly required for the activation of inward K+ channels in the guard-cell plasma membrane.
  • ATP acts as a direct signal molecule to regulate the activity of these K+ channels.
  • Further research is needed to understand the precise mechanism of ATP-mediated channel regulation.

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